Is it permissible to sleep, eat, and drink when one is in the state of janabah?

A junub person cannot perform certain acts of worship and Islamic duties such as establishing prayer and reciting the Qur’an. Therefore, he should try to get purified from this condition which prevents him from performing his worships by performing ghusl as soon as possible.

However, a person who needs to perform ghusl, if needed, may sleep, eat and drink, and deal with other things by performing ablution after cleaning his private parts or only washing his hands and mouth, on condition that it does not cause to miss a prayer time (Bukhari, Ghusl, 27; Muslim, Haidh, 21, 22, 24). Because being junub does not prevent one from doing things that do not require a special cleaning such as ablution and ghusl. Indeed, the Prophet (saw) said that a Muslim would not be considered as physically unclean when he is junub (Bukhari, Ghusl, 23).

Yet it is haram for a junub person to postpone washing oneself in a way to miss the prayer time, and it is makruh to eat and drink without washing his hands and mouth. In this respect, such person should perform ghusl and get washed and cleaned as soon as possible if there is no compulsory situation.

Source: Presidency Of Religious Affairs The Turkey, High Board of Religious Affairs FATWAS

What Should A Person Who Has Waswasa (Extreme Anxiety Or Misgivings) While Performing Ghusl And Minor Ablution Do?